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CVE-2026-63344

Refitter: C# source injection through OpenAPI content-type map keys

8.6 High

Refitter is a tool for generating a C# REST API client using the Refit library. Prior to 2.1.2, content-type keys in the content maps of requestBody/responses are emitted verbatim into a Refit [Headers("Accept: <ct>", "Content-Type: <ct>")] attribute string without escaping quotation marks. A crafted content-type key in an attacker-influenced OpenAPI description survives default validation without --skip-validation, breaks out of the attribute string and enclosing interface and namespace, and can introduce a top-level file class while leaving valid generated C#. A [ModuleInitializer] method in that class executes attacker code when the generated assembly is loaded at application startup, without requiring a call to the client. The behavior was verified with Refitter 2.0.0 and .NET 8. This issue is fixed in version 2.1.2.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Active

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
High

Exploit likelihood

0.35%Unchanged since Oct 31, 2026
90%50%10%1%

What each source reports

CVE List Score used 8.6

Refitter: C# source injection through OpenAPI content-type map keys

Refitter is a tool for generating a C# REST API client using the Refit library. Prior to 2.1.2, content-type keys in the content maps of requestBody/responses are emitted verbatim into a Refit [Headers("Accept: <ct>", "Content-Type: <ct>")] attribute string without escaping quotation marks. A crafted content-type key in an attacker-influenced OpenAPI description survives default validation without --skip-validation, breaks out of the attribute string and enclosing interface and namespace, and can introduce a top-level file class while leaving valid generated C#. A [ModuleInitializer] method in that class executes attacker code when the generated assembly is loaded at application startup, without requiring a call to the client. The behavior was verified with Refitter 2.0.0 and .NET 8. This issue is fixed in version 2.1.2.

Record
CVE-2026-63344
CVSS 4.0
8.6 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-94, CWE-116
Updated
2026-11-06
EUVDEUVD-2026-114539 8.6

Refitter is a tool for generating a C# REST API client using the Refit library. Prior to 2.1.2, content-type keys in the content maps of requestBody/responses are emitted verbatim into a Refit [Headers("Accept: <ct>", "Content-Type: <ct>")] attribute string without escaping quotation marks. A crafted content-type key in an attacker-influenced OpenAPI description survives default validation without --skip-validation, breaks out of the attribute string and enclosing interface and namespace, and can introduce a top-level file class while leaving valid generated C#. A [ModuleInitializer] method in that class executes attacker code when the generated assembly is loaded at application startup, without requiring a call to the client. The behavior was verified with Refitter 2.0.0 and .NET 8. This issue is fixed in version 2.1.2.

Record
EUVD-2026-114539
CVSS 4.0
8.6 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-06
NVD 8.6

Refitter is a tool for generating a C# REST API client using the Refit library. Prior to 2.1.2, content-type keys in the content maps of requestBody/responses are emitted verbatim into a Refit [Headers("Accept: <ct>", "Content-Type: <ct>")] attribute string without escaping quotation marks. A crafted content-type key in an attacker-influenced OpenAPI description survives default validation without --skip-validation, breaks out of the attribute string and enclosing interface and namespace, and can introduce a top-level file class while leaving valid generated C#. A [ModuleInitializer] method in that class executes attacker code when the generated assembly is loaded at application startup, without requiring a call to the client. The behavior was verified with Refitter 2.0.0 and .NET 8. This issue is fixed in version 2.1.2.

Record
CVE-2026-63344
CVSS 4.0
8.6 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness
CWE-94, CWE-116
Updated
2026-11-06
OSV 8.6

Refitter: C# source injection through OpenAPI content-type map keys

Refitter is a tool for generating a C# REST API client using the Refit library. Prior to 2.1.2, content-type keys in the content maps of requestBody/responses are emitted verbatim into a Refit [Headers("Accept: <ct>", "Content-Type: <ct>")] attribute string without escaping quotation marks. A crafted content-type key in an attacker-influenced OpenAPI description survives default validation without --skip-validation, breaks out of the attribute string and enclosing interface and namespace, and can introduce a top-level file class while leaving valid generated C#. A [ModuleInitializer] method in that class executes attacker code when the generated assembly is loaded at application startup, without requiring a call to the client. The behavior was verified with Refitter 2.0.0 and .NET 8. This issue is fixed in version 2.1.2.

Record
CVE-2026-63344
CVSS 4.0
8.6 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-116, CWE-94
Updated
2026-11-07

Affected products

History

History
RecordedChangedSources
referencesCVE List
factsNVD, OSV
first indexedCVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-63344 is a high vulnerability (CVSS 8.6) in Christianhelle Refitter, published October 30, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.35%, the 28th percentile. No source names a fixed version.

References

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